1. Sort out some of the hover-state link colors.
2. Add username/password as default in the fields at the top, otherwise 'some' people/clients may not know what it is.
3. On the homepage banner, you could have used a sprite on those hover images, that way there's only 1 image to load and not 4.
4. The background gradient needs more work on each side.
5. Get rid of the portfolio items on the portfolio dropdown, actually, get rid of the drop down altogether. The portfolio section is considered the showcase of your companies skill level. In which case you should really show off.
So change the whole thing so when you click portfolio, on this page, you have various thumbnails / title / small description of each piece. Which then will click through to highly detailed project page, perhaps with larger screenshots or even multiple 'scrollable' screenshots of the work.
6. The last item 'support' on the menu, make the dropdown not overlap the site width. Bring it inwards.
7. Thats about it.

Apart from taking the seo perspective, a design perspective would help for improvement.